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# __init__.py

Here's a documentation for the `cassiopeia/__init__.py` file:

## High-level description

This file serves as the top-level initialization for the Cassiopeia package. It imports and exposes key submodules, sets up version information, and configures the package namespace.

## Code Structure

The file imports various submodules of Cassiopeia and makes them available at the top level of the package. It also sets up version information using importlib.metadata and configures the package namespace.

## Symbols

### Imported submodules

#### Description

The following submodules are imported and made available at the top level of the Cassiopeia package:

* `preprocess` (aliased as `pp`)
* `solver`
* `plotting` (aliased as `pl`)
* `data`
* `critique`
* `simulator` (aliased as `sim`)
* `tools` (aliased as `tl`)

These imports allow users to access these submodules directly from the Cassiopeia package.

### `__version__`

#### Description

Stores the version number of the Cassiopeia package.

#### Internal Logic

The version is retrieved using `importlib.metadata.version()` with the package name "cassiopeia-lineage". This allows for dynamic version retrieval based on the installed package metadata.

### Package namespace configuration

#### Description

Configures the package namespace to allow direct access to certain submodules.

#### Internal Logic

The `sys.modules` dictionary is updated to allow direct access to the `tl`, `pp`, `pl`, and `sim` submodules from the Cassiopeia package namespace. This means users can access these submodules directly, e.g., `cassiopeia.tl` instead of `cassiopeia.tools`.

## Dependencies

| Dependency          | Purpose                                                         |
| :------------------ | :-------------------------------------------------------------- |
| importlib.metadata  | Used for retrieving the package version                         |
| importlib\_metadata | Fallback for Python versions that don't have importlib.metadata |

## Error Handling

The code includes a try-except block to handle potential `ModuleNotFoundError` when importing `importlib.metadata`. If this import fails, it falls back to using `importlib_metadata`.

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